At 1439 Pacific time, the accident aircraft made a forced landing near Perris, Calif., following loss of engine power. Neither the Private pilot nor his four passengers were injured; however, the airplane sustained substantial damage. Visual conditions prevailed for the cross-country flight. The pilot subsequently stated that he leveled the airplane at 10,500 feet msl after its initial climb. While configuring the airplane for cruise, he noticed the oil pressure needle was in the yellow-green arc transition area, with the oil warning light flickering intermittently. The pilot then decided to turn back to his departure airport. About five minutes later, the engine started to vibrate and subsequently seized. The selected a dirt field on which to perform an emergency landing. On touching down, with the airspeed at about 110 knots, the airplane impacted a berm, the nosegear collapsed and the airplane came to rest on its nose.